1. Field of the Invention
This invention relates generally to chemical water treatment and more particularly to a system by which a solid chemical cake may be dissolved and fed under controlled conditions for use in a downstream application.
2. Description of Related Art
The following art defines the present state of the field of the present invention, and each disclosure is hereby incorporated herein by reference:
Yao et al., U.S. 2004/0151062, discloses a novel interlocked automatic chemical mixing system and method of use which is particularly well-suited to preparing a final diluted HF (hydrofluoric acid) mixture of desired concentration for the post-cleaning rinsing of semiconductor wafer substrates. The automatic chemical mixing system includes a mixing tank having a normal level sensor and a mixing level sensor above the normal level sensor. A mixing system is provided for thoroughly mixing the liquid precursor components in the mixing tank. In typical application, DI water is introduced into the mixing tank until the DI water reaches the level of the mixing sensor. The precursor aqueous HF is then introduced into the mixing tank until the level of the HF reaches the normal level sensor.
Littlejohn, U.S. Pat. No. 3,695,485, discloses a unit system adapted to feed any number of liquid destinations on demand, especially dangerous liquids, and comprising a protected storage of said liquid, a motor driven pump means supplying said liquid into a holding means, a safety inlet valve governing flow of liquid from said pump means and into the holding means, and a flow outlet dispensing the said liquid; the invention residing in a motor and safety inlet control means responsive to high and low level sensors in said holding means so as to maintain a normal level therein, outlet safety means responsive to excessive flow in said outlet from the holding means and closing the safety inlet valve, and overflow safety means responsive to flooding of the holding means and overriding the motor control means. Utility resides in the adaptability to multiple installations wherein the fluid circuitry of each unit remains individually operable and protected while drawing from a common storage and motor driven pump means.
Heiser, Jr., U.S. Pat. No. 4,770,859, discloses a device for dispensing a caked composition into a liquid that employs a container filled to a desired level with a cake of the composition to be dispensed, and an upwardly opening vessel over which to place the container telescopically so that the cake surface is disposed over the vessel mouth. A support structure is included upon which the vessel is mounted in a position enabling placement of the container over the vessel, the support structure serving to support the vessel so that the vessel mouth is facing upwardly and the rim portion is disposed horizontally. Liquid coupling components couple a flow of liquid from a separate source through an inlet opening in the vessel, so that with the cake surface disposed over the vessel mouth, the liquid fills the vessel, washes across the cake surface to dispense the composition from the cake, and then discharges over the rim portion.
Copeland et al., U.S. Pat. No. 4,826,661 discloses a dispenser for and method of dispensing a concentrated cleaning solution from a solid block of a cleaning composition wherein the concentrated cleaning solution is dispensed at a substantially constant concentration during the entire useful life of the solid block of cleaning composition. The dispenser comprises (i) a spray nozzle for directing a uniform dissolving spray onto an exposed surface of the solid block of cleaning composition; and (ii) a spring or hydraulic piston coupled to the nozzle for biasing the nozzle towards the solid block and thereby maintaining a substantially constant distance between the nozzle and the exposed surface of the solid block of cleaning composition even though the exposed surface recedes due to dissolution by the dissolving spray.
Gulmatico, Jr., U.S. Pat. No. 4,830,509, discloses a device that is provided for dissolving dry detergent to provide a liquid detergent solution to washing machines in a laundry. A tank is divided into upper and lower compartments. The upper compartment drains into the lower compartment when a tank valve there between is opened, and the compartments are maintained in mutual isolation when the tank valve is closed. High and low liquid level sensors in the upper compartment control mixing and dispensation of detergent solution. A quantity of dry, solid powdered detergent is mixed with a predetermined quantity of water in the upper compartment while the upper and lower compartments are isolated from each other during a mixing cycle. During the mixing cycle the lower compartment serves as a reservoir for supplying liquid detergent solution to one or more washing machines. Following the mixing cycle, the contents of the upper compartment are allowed to drain into the lower compartment.
Edstrand et al., U.S. Pat. No. 5,680,877 discloses a method of and system for cleaning and maintaining water distribution pipes which have reduced flow due to an increase of water scale deposits, sediment and the like along the inside surface of the pipe that includes a mobile cleaning unit which can be conveniently and easily connected to a pipe section to be cleaned. An aqueous cleaning solution is introduced and circulated in a first direction through the pipe section for sufficient time to dissolve and loosen scale and sediment. The flow direction of the treating solution is then reversed to break off or remove sediment or other tuberculated growth that has developed directionally with the direction of water flow in the pipe section. The turbulent flow in the opposite direction increases the effectiveness of the cleaning process in particularly troublesome and hard-to-clean pipe sections. The spent treating solution and other deposits are flushed from the pipe and the mobile cleaning unit to an appropriate waste stream. Advantageously, the direction of the flow of the treating solution can be reversed without disconnecting the cleaning unit from the pipe section.
Werre et al., U.S. Pat. No. 5,706,841 discloses an invention that relates to an arrangement for automatically cleaning heat-exchanging passageways, particularly the coolant passageways of tools. According to the invention, the arrangement includes an outlet line, an inlet line and connections for connecting the outlet line and the inlet line to a respective inlet and outlet of the passageway or passageways to be cleaned; a liquid tank; a pump and associated lines for filling the tank with cleaning liquid or with rinsing liquid; a pump and associated lines for circulating liquid from the tank in a closed circuit through the passageway or passageways to be cleaned; and a microprocessor for performing automatically the operations of filling the tank with cleaning liquid, circulating cleaning liquid through the heat-exchanging passageway or passageways, emptying the tank of cleaning liquid, filling the tank with rinsing liquid and circulating the rinsing liquid in the heat-exchanging passageway or passageways, and emptying the tank and the heat-exchanging passageway or passageways of rinsing liquid.
List et al., U.S. Pat. No. 5,961,845 discloses a dispenser system for treating water containing systems in place with a dry chemical substance. The dispenser has a water soluble pouch housing a dry form of a chemical material to be used in treating the system. The pouch is positioned in a make down unit so that the chemical is dissolved to form a liquid concentrate which is then introduced into a water containing system. A controller is attached to the make down unit to regulate the flow of water into the apparatus and the flow of liquid concentrate out of the apparatus and into the water-containing system.
Schwanberger et al., U.S. Pat. No. 6,779,539, discloses an apparatus to dispense water soluble compositions into a process stream that involves recirculating water through the water soluble chemical held in a tank. The recirculating water is heated to establish a defined temperature and repeatedly recirculated through the bed of chemical to achieve relative saturation concentration of the recirculating water. The water is dispensed from the recirculating unit thereby achieving a consistent concentration of chemical in the dispensed water.
Our prior art search with abstracts described above teaches: a solid product system and method of use; an automatic system for dissolving dry detergent; a dispensing apparatus for delivering controlled amounts of water soluable material to a process stream; an arrangement for cleaning automatically heat-exchanging passageways, particularly tool-coolant passageways; a solid block chemical dispenser for cleaning systems; an automatic safety feed system for liquids; a dispenser for chemicals; a system and method for cleaning water distribution pipes; and an automatic chemical mixing system. Thus, the prior art discloses the use of systems and methods for dissolving solid chemical cakes and powders in a solute under automatic control and the use of such chemicals for the cleaning of such systems and similar applications. However, the prior art fails to teach a dissolving system using a dissolving tank and a gravity fed holding tank wherein the dissolving process is controlled by the amount of dissolved chemical in the holding tank, i.e., wherein the inventory solution is generated in proportion to the level of solution in the holding tank. The present invention fulfills these needs and provides further related advantages as described in the following summary.